The present invention relates generally to aircraft environmental control systems (ECS), and in particular to a system and method for controlling ram air flow within an aircraft ECS.
An aircraft ECS often includes one or more heat exchangers configured to provide air-to-air cooling for bleed air. The bleed air may be provided to the heat exchangers from an aircraft engine, for example, and be cooled, by the heat exchangers, using ram air flow. A controller for the system is configured to control a ram actuator to control a ram inlet door position, for example, to control the ram air flow to the heat exchangers based on a desired downstream temperature of the bleed air. However, both controlling the ram air flow by controlling the ram inlet door position and controlling the inlet door position by controlling a ram actuator command are non-linear, resulting in imprecise temperature control within the system. It is desirable to increase the precision of the final bleed air temperature control without greatly increasing the complexity and cost of the system.